The present invention relates to a device for injecting a resin into at least one fibre layer of a fibre-reinforced product to be manufactured, comprising a mould having a mould cavity that is surrounded by a mould wall for abutment of the product thereagainst in the closed condition of the mould. More specifically, the invention is directed at a device by means of which fibre-reinforced constructional members can be manufactured, in particular for use in aircraft, for example as (a part of) landing gear systems, propeller blades and helicopter blades, and especially hollow constructional members.
It is known to use a liquid moulding technology referred to as RTM (Resin Transfer Moulding) for manufacturing such constructional members. The device according to the introductory paragraph is known in relation to the use of said RTM technology. With this technology, the fibre reinforcements are first completely assembled into a preform, after which said preform is injected with the liquid resin in a negative mould. Traditionally an inner mould and an outer mould defining a mould cavity between them have been used for forming hollow constructional members. The fibre reinforcements are placed more or less in the form of a mat in said cavity, after which liquid resin is injected into the mould cavity and thus into the fibre reinforcements. After curing, the product thus formed is removed from the mould to be subjected to further processing steps in order to obtain a fibre-reinforced constructional member as the final product.
A problem that occurs during the curing process of the resin is that a certain degree of shrinkage of the resin may take place, to the extent of a few percent (for example two to three percent), as a result of which the product tends to come loose from the mould wall against which the product abuts at the start of the injection process. This may lead to the formation of external but also internal cracks in the material, for example caused by delamination, and/or to imperfections at the surface. These negative effects increase as the thickness of the material of the product increases.